white



No. 6l8,260. Patented Ian. 24, I899. C. P. WHITE.

OVEN THERMOMETEB.

(Application filed Aug. 18, 1898.)

3 Sheets$heet I.

(No Model.)

No. 6l8,260. Pateritufl 115. 2 4, lime.

c. P. wumz. v

OVEN THERIOIIETER.

(Application mod Aug. 18, 1898.)

(No Model.) 3 Sheets-Sheet 2.

ki\ \jQ N i I Q-Q q f ayh q i 5 Q Q s N R 3 a fi g mg A .(0 E M tolflv'nesses: 77/7/677/Z071' No. 618,260. Patented Jan. 24, I899. C. P.WHITE.

OVEN THERMOMETER.

(Application filed Aug. 18, 1898.) (No Model.) 3 Sheets-Sheet 3.

AIS 1g. A?

Wain/asses.- Invenbr;

C JMMJ? r6414 w. M

time 7 STATES PATENT Trice.

CHARLES P. WHITE, OF TAUNTON, MASSACHUSETTS, ASSIGNOR TO THE IVHITEWVARNER COMPANY, OF SAME PLACE.

OVEN-THERMOMETER.

SPECIFICATION forming part of Letters Patent No. 618,260, dated January24, 1899.

Application filed August 18,1898. Serial No. 688,855. (No model.)

chusetts, have invented certain new and useful Improvements inOven-Thermometers, of which the following is a specification.

My invention relates to a thermometer for use in combination with anoven or other closed chamber which is to be heated to a high degree toindicate to an observer 0n the outside the temperature within the ovenor chamber.

The several features of my invention will now be fully described andwill be particularly pointed out in the claims at the end of thespecification.

In the drawings, Figure 1 is a front elevation, partly in section, of myoven-thermometer detached from the oven-door. Fig. 2 is a plan of theunder side of Fig. 1, partly in section. Fig. 3 is a section on line 3 3of Fig. 2. Fig. 4 is a cross-section on line at at of Fig. 1, showingalso a section of the oven-door.

Inclosed in a metal tube 1, preferably of brass or other metal which ishighly expansive when heated, are two springs 2, which lie lengthwise ofthe tube, being spread apart at the middle and converging toward eachotherat the ends. At one end the said springs are secured to the washer3, which is fixed in the end of the tube. At their other end the saidsprings are entered between the converging sides A of the sliding box 6,the ends of the springs abutting against the head of said box. In theend of the tube is a washer '7, through which passes a screw 8, whichbears against the head of the sliding box 6. By setting up the screw 8the sliding box 6 is pushed forward in the tube, and the springs 2 arethereby adjusted to the proper tension for use. By turning back thescrew the tension is reduced.

The tube 1 is clamped between the arms 12, which project rearwardly fromthe dial-box 11 and the yoke 9, which is secured by screws 10 to theback of said dial-box. The tube 1 is prevented from turning by a lug 13,which projects from the inside of the yoke 9 into a hole in the side ofsaid tube. Projecting from the side of one of the springs 2 is a bracket14, which forms a bearing for the arbor 15. Said arbor passes throughthe dial-box and carries on its outer end an index-hand 16. On the arbor15 is a pinion 17, which engages with a rack 18, projecting from thespring 2 other than the one to which the bracket 14 is attached. Thedial-box 11 is secured to the oven-door 19, through which is an openingto expose the dial 20, which closes said opening. On the inside of theoven-door is a flange 21, which helps to support the dial-box and is cutaway at the upper part, so that the index-hand 10, which is longer thanthe radius of the opening for the dial, may have freedom to move betweenthe door and the dial-box. The portion of the dial which the handtraverses is graduated to degrees of heat. When the oven is heated, thetube 1 is correspondingly heated and expands in length, so that thesliding box can accordingly yield somewhat to the pressure of thesprings, thus reducing the tension. As the tension is reduced thesprings tend to assume a more straight form and draw nearer together atthe middle portions. In so doing the rack 18 is moved also, therebyturning the pinion l7, and the index-hand will indicate on the dial thede gree of temperature in the oven.

The form of support for the tube and its mode of attachment to theoven-door may be varied without departing from my invention, the mainfeatures of which are the expansion-tube, the springs, and the mechanismactuated thereby to turn the arbor on which the index-hand is mounted.

What I claim as my invention is- 1. In an oven-thermometer an expansivemetal tube, two springs in said tube lengthwise thereof spread apart attheir middle portions and converging toward the ends, the ends of thesprings at one end of the tube being secured against spreading, asliding box at the other end of the tube which receives the ends of saidsprings, a rack projecting from the inner wall of one of said springs, abracket projecting from the inner wall of the second of said springs, anarbor having its bearings in said bracket, an index-hand carried by saidarbor, and a pinion on said arbor which engages with said rack wherebywhen the tube is expanded by heat the springs will be drawn toward eachother at the middle thereby turning the arbor and index-hand,substantially as described.

2. An oven-thermometer having a tubular casing which is expansible byheat, two springs in said tube lengthwise thereof spread apart at theirmiddle portions and converging toward the ends, the ends of the springsat one end of the tube being secured against spreading, a sliding box atthe other end of the tube which receives the ends of said springs andprevents spreading thereof,a rack projecting from the inner wall of oneof said springs, a bracket projecting from the inner wall of the secondof said springs, an arbor having its bearing in said bracket and apinion on said arbor which engages with said rack whereby when the tubeis expanded by heat the springs will be drawn toward each other therebyturning the arbor, an indexhand on the end of said arbor, a dialtherefor, and a frame to which said tubular casing is secured, incombination with an oven-door to which said frame is secured, theoven-door having a reading-opening for the dial, and having on theinside of the door around the said openinga flange which partiallysupports the thermometer-frame and leaves a space between the door andthe dial-box for the movement of the index-hand, substantially asdescribed.

3. In an oven-thermometer, an expansive tubular casing, two springslengthwise of said casing spread apart at their middle portions andconverging toward their ends, means for preventing the springs fromspreading apart at the ends so that when the tube is expanded thesprings will be drawn toward each other at their middle portions, anarbor carrying an index hand and mechanism which is actuated by themovement of the springs to turn the said arbor and index-hand,substantially as described.

I. In an oven-thermometer, an expansive tubular casin g, two springslengthwise of said casing spread apart at their middle portions andconverging toward their ends, means for preventing the springs fromspreading apart at the ends so that when the tube is expanded thesprings will be drawn toward each other at their middle portions, anarbor carrying an index-hand, mechanism which is actuated by themovement of the springs to turn the arbor and index-hand, a sliding boxin said tubular casing at one end thereof which receives the ends of thesprings, and a regulating-screw in the tube acting on a sliding boxwhereby the proper tension may be given to the springs, substantially asdescribed.

In testimony whereof I have affixed my signature in presence of twowitnesses.

CHARLES P. W HITE.

Witnesses:

\VILLIAM A. COPELAND, OSCAR F. HILL.

